<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .box {
            background-color: pink;
            width: 100%;
            height: 100%;
        }

        .inner {
            background-color: red;
            width: 80px;
            height: 100px;
        }
    </style>
    <script src="/vue.js"></script>
</head>
<body>
    <div id="app">
        <div v-bind:class="{box}">我是box
            <div v-bind:class="{inner}">我是inner1</div>
            <div v-bind:class="{inner}">我是inner2</div>
        </div>
    </div>
    <script>
        var vue = new Vue({
            el: "#app",
            data: {
                box: "box",
                inner: "inner"
            }
        })
    </script>
</body>
</html>